Method of combining optical brighteners with polymers for stability in bleach and encapsulated product

ABSTRACT

Optical brighteners are protected against oxidative degradation by aggressive environments such as aqueous hypochlorite bleach to be effectively depositable onto fabrics from bleach by combining the brightener with emulsion polymer prepared from a major portion of the polymer precursors and encapsulating the brightener-polymer combination with the balance of the polymer precursors. Suitable precursors are styrene and acrylic or methacrylic acid, in weight ratios of 65 to 98 parts of the former to two to 35 parts of the latter.

United States Patent Briggs 1 51 May 30, 1972 [21] Appl. No.: 16,926

52 us. c1 ..'...2s2/3'1'6, 8/79, lots/308M; 106/308 N, 117/100 A,117/100 B, 252/95,

252/010. 2, 260/29.6 MN, 260/29.6 MQ, 260/296 RB, 260/29.6 RW, 260/29.6T, 260/29.6 TA

51 1111.0. .1101,- 13/02, B44d 1/14 [58] Field 61 Search ..252/316,95,187; 117/100 A [56] References Cited UNITED STATES PATENTS 3,544,50012/1970 Osmond et a1. ..252/3 1 6 X 3,401,123 9/1968 3,213,053 10/19652,969,331 1/1961 Brynko et a1. ..252/316 3,393,153 7/1968 Zimmerer eta1. ..252/95 Pn'mary Examiner-Richard D. Lovering Attomey-White,Haefliger and Bachand ABSTRACT Optical brighteners are protected againstoxidative degradation by aggressive environments such as aqueoushypochlorite bleach to be effectively depositable onto fabrics frombleach by combining the brightener with emulsion polymer prepared from amajor portion of the polymer precursors and encapsulating thebrightener-polymer combination with the balance of the polymerprecursors. Suitable precursors are styrene and acrylic or methacrylicacid, in weight ratios of 65 to 98 parts of the former to two to 35parts of the latter.

20 Claims, No Drawings METHOD OF COMBINING OPTICAL BRIGHTENERS WITHPOLYMERS FOR STABILITY IN BLEACH AND ENCAPSULATED PRODUCT BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention has to do withprotecting optical brighteners from oxidative degradation by aggressivechemicals. More particularly the invention is concerned with meansenabling incorporation of oxidation sensitive compounds into oxidizingenvironments such as hypochlorite bleach solution for subsequentdeposition onto fabric without loss of brightening effectiveness throughoxidative destruction.

The invention further concerns provision of opacifiers for bleach andother aggressive chemical solutions to improve the esthetic appearanceof such solutions.

2. Prior Art The use of opacifiers in bleach is taught in e.g. Zimmerer,US. Pat. No. 3,393,153, issued July 16, 1968. The combination of apolymer latex with optical brighteners has also been suggested in orderto carry onto the fabric chemicals which brighten what bleach haswhitened.

Brightening of fabrics has been realized in the past through the use ofparticular dyes termed optical brighteners in detergents. While bleachfunctions to remove colored impurities from fabrics by chemicalconversion e.g. into colorless products by'oxidation and bluing offabrics renders undesired yellow color invisible by color compensation,brighteners operate to compensate for a yellow cast in fabric occasionedby absorption of short wavelength blue light by yellow bodies in thefabric by a partial replacement of the absorbed or lost" light. This waythe eye sees a complete white, without loss of light. Opticalbrighteners absorb the invisible ultraviolet portion of the daylightspectrum and convert the energy there into blue visible light throughfluorescence. Optical brightening thus effectively adds light tofabrics.

The conjoint use of detergent and bleach however as in a typicalhousehold wash operation may destroy portions of the optical brightenerthrough oxidation by the bleach. Thus the net whitening and brighteningis not strictly additive.

The combination of optical brightener with bleach would result in higherlevels of brightener in the wash water if the brightener could bepreserved while in the bleach. Zimmerer, above noted, suggests heating apolymer latex and brightener together to so associate the brightener andpolymer that the stability of the latter will somehow accrue to thebenefit of the former. This result is not achieved, however, if there isaccess of bleach to the brightener.

It is necessary to exclude bleach-brightener contact in bleach solutionsand in wash water if the full benefits of brighteners is to be realized.

SUMMARY OF THE INVENTION Accordingly, it is an object of the inventionto provide method means for combining optical brighteners, and otherdyes, with synthetic organic polymer in a manner protective of thebrightener when in contact with aqueous bleach solution.

This and other objectives of the invention, to be made apparent as thedescription proceeds, are realized by the method of combining opticalbrightener compound with synthetic organic polymer consistingessentially per 100 parts by weight of 65 to 98 parts of a styrenemonomer having eight to 12 carbon atoms and two to 35 parts of a watersoluble monocarboxylic acid having three or four carbon atoms in amanner to retain optical brightening properties in aqueous bleachsolutions which includes the steps of:

a. dissolving optical brightener compound in a major weight proportionbut less than 90 percent by weight of said styrene monomer;

b. dissolving at least a major weight proportion of said vinyl acid inwater;

c. combining the optical brightener containing styrene monomer from step(a) with the aqueous vinyl acid solution of p d. emulsion polymerizingthe mixture of step (c) to form a copolymer latex incorporating theoptical brightener compound in the particulate copolymer so formed;

e. adding the balance of the styrene monomer and the balance of thevinyl acid monomer, if any, to the latex from step (d), and;

f. emulsion polymerizing the added monomers in step (e) onto thecopolymer particles from step (d).

Means thus are provided for protectively carrying oxidizer sensitivecompounds in aqueous bleach comprising particles having an inner portionconsisting essentially of an oxidizer sensitive compound and astyrene-acrylic polymer and an outer portion forming an encapsulatinglayer over the inner portion and consisting essentially of styrenepolymer free of the brightener compound. The particle comprises per 100parts of polymer from 65 to 98 parts of a styrene monomer having eightto 12 carbon atoms and conversely from two to 35 parts of methacrylic oracrylic acid copolymerized therewith. The particle inner portioncontains a major proportion but less than percent by weight of thestyrene content of the particle and at least a major weight proportionof the acid monomer, with the balance of the monomers being con tainedin the particle outer portion forming the encapsulating layer.

The oxidation sensitive compound is generally an optical brightenerwhich may be selected from 4,4'-diaminostilbene 2,2 disulfonic acids,dibenzothiophene -5,5- dioxides and azoles and be present in an amountbetween 0.5 and 5 percent by weight based on the weight of the styrene.The polymer particles typically range from 0.1 to 2 microns in averagepar ticle size. A portion of the styrene component e.g. five to 10 partsby weight per 100 parts of the polymer, may be replaced by five to 10parts of a hydrophilic monomer selected from the hydroxyester, ether,amide and cyano derivatives of acrylic or methacrylic acid or a vinylsulfonate monomer having the formula R--Cl-l Cl-l--SO Me in which R ishydrogen or an aromatic or alkyl radical having up to 10 carbon atomsand Me is alkali metal.

The safe incorporation of optical brighteners and other dyes andoxidation susceptible compounds in aggresive environments such asaqueous bleach is realized by combining the brightener in a polymer in amanner to insulate the brighteners from the harsh environment whilepermitting its useful brightening function. To so combine the brightenercompound with polymer, the brightener is first dissolved in the oilsoluble monomer of the polymer and the monomer-brightener solution iscopolymerized with vinyl acid, i.e. acrylic or methacrylic acid whichhas been previously dissolved in water, by conventional emulsionpolymerization techniques. Subsequently a second emulsion polymerizationis effected to coat the particles resulting from the firstpolymerization with a bleach impervious polymer free of brightener thusto protect the brightener compound in the first or inner center portionof the polymer particle. While the emulsion recipes are conventional,the sequence of operations is not conventional and enables therealization of the invention.

It is known to emulsion polymerize styrene and acrylic acid bydissolving an emulsifying agent in all the water and adding the acrylicacid and possibly a hydrophilic comonomer. Styrene or other oil soluble,principal monomer is added to the mixture and stirred to achieveemulsification. The temperature of the emulsion is raised to l20140 Fand a persulfate or peroxide catalyst is added with or without areducing agent to form a redox couple to produce free radicals toinitiate the polymerization reaction. The temperature of the emulsionrises exothermically as the monomer species are converted into polymer.Usually no external heat is required and almost all of the monomer ispolymerized to provide a milky aqueous suspension of particles (a latex)in which the particles typically range from 0.1 to 2 microns in averageparticle size and contain about 30 to 60 percent of the total polymer.

In the present invention, the above common procedure is modified toachieve the purposes of the invention. Thus only a portion of themonomer components are first reacted together. And the brightener isfirst dissolved in the oil soluble monomer (styrene) to assure intimateincorporation of the brightener compound in the polymer. in a secondstage of the preparation the balance of the monomers is added and aftersufficient interrnixing and addition of catalyst, a second emulsionpolymerization is effected to overcoat the first formed particles withadditional, separately formed polymer which it has been found willprotect the brightener in the first stage polymer.

While not wishing to be bound to any particular theory of operation itis believed the remarkable stability of the brightening compound in theproducts of the invention against oxidative attack may derive from theformation of micelles upon the addition of the emulsifier-surfactant towater. The micelles are larnellar colloidal particles having structuresdependent on the hydrophobic/hydrophilic orientation of the surfactantmolecule. Upon the addition of the hydrophobic (styrene) monomercontaining dissolved dye in the first stage of preparation, thesemonomer droplets and hydrophilic monomer become encapsulated in themicelles. Addition of catalyst causes polymerization to proceed withinthe confines of the micelle until a hard, discrete particle of polymerif formed, still enveloped by the micelle structure. Upon the additionof the second portion of the hydrophobic (styrene) monomer, in theabsence of additional surfactant for formation of new micelles the addedmonomer enters the previously formed polymer particle micelles and formsa layer of reactive monomer over the outside of the polymer particles.With the addition of more catalyst, this newly added monomer polymerizesand forms a shell of basically hydrophobic polymer over the innerparticle portion containing the brightener compound. This shell preventschemically active molecules such as oxidizing molecules of bleach fromentering the particle to the brightener compound. The second addedportion of hydrophobic monomer may contain brightener compound, but suchcompound in the outer layer of the particles is readily destroyed incontact with bleach.

The particulate polymer in which the brightener compound protectivelyinheres consists essentially of a styrene monomer, acrylic ormethacrylic acid and optionally a hydrophilic comonomer.

As the hydrophobic monomer component there may be employed styrene perse, i.e. vinyl benzene, or a substituted styrene such as vinyl tolueneor butyl styrene i.e. alkyl substituted styrenes in which the alkylgroups contain from 1 to 4 carbon atoms such that the styrene monomercontains from 8 to 12 carbon atoms, inclusive. Or the styrene monomermay be monohalogen ring substituted such as chlorostyrene orbromostyrene. The acid component may be described generically as a watersoluble a, B ethylenically unsaturated monocarboxylic acid, i.e. vinylacid having three to four carbon atoms namely acrylic or methacrylicacids. The proportion by weight of combined styrene monomer and acidmonomer is the particulate polymer ranges between 65 to 98 parts styreneand two to 35 parts of the vinyl acid per 100 parts by weight of theterpolymer.

Polymerization is carried out as hereinafter described to providepolymer particles ranging in size between 0.01 and microns andpreferably between 0.1 and 2 microns where an opacifying effect isdesired. It is often desirable to incorporate a further hydrophylicmonomer in the polymer such as a derivative of methacrylic or acrylicacid containing up to carbon atoms and free of carboxyl groups, such asester, hydroxyester, ether, amide or cyano derivatives of acrylic ormethacrylic acids. These may be used in amounts of between 0.5 and 25parts by weight and preferably from five to 10 parts, in substitutionfor an equal weight amount of the styrene monomer, per 100 parts of thefinal opacifying polymer. A

water soluble vinyl sulfonate monomer may be the additional hydrophiliccomponent e.g. having the formula R-CH CHSO Me .in which R is ahydrocarbon radical free of aliphatic unsaturation having up to 10carbon atoms e.g. an aromatic radical such as tolyl, benzyl or phenylradical; an alkyl radical such as methyl, ethyl, propyl, butyl,isobutyl, pentyl, neopentyl, hexyl, heptyl, octyl, 2-ethyl hexyl, nonyland decyl, or hydrogen and Me is an alkali metal e.g. sodium, potassium,lithium and cesium. Specific termonomers of choice include thehydroxyalkyl esters of methacrylic acid in which the alkyl groupcontains from one to four carbon atoms and particularly hydroxyethyl andhydroxypropyl methacrylate, and acrylarnide, methacrylamide,acrylonitrile, methyl vinyl ether, sodium or potassium vinyl sulfonateand styrene sulfonate.

The monomers just described are emulsion polymerized using conventionalcatalysts, oxidizers or reducers, temperatures and pressures but withthe critical steps of first dissolving the brightener compound in thestyrene monomer and dissolving the water soluble vinyl acid andhydrophilic comonomer, if used, in water, suitably with the emulsifyingsurfactant, prior to addition of the styrene. Apart from the hereindiscussed sequential reactant additions, the preparation of the polymersis carried out as for any other exothermic emulsion polymerization ineach stage. Thus an aqueous solution of a suitable surfactant is mixedwith the water soluble vinyl acid. Thereafter the water insolublestyrene reactant into which the brightener compound has been previouslydissolved, suitably at concentrations between 0.5 and 5 percent based onthe total of styrene in the polymer and preferably at least I percent byweight same basis, is mixed in and agitated until emulsified as the oilphase. The emulsion is then maintained at an elevated temperaturethrough-exothermic and/or added heat if necessary in admixture with asuitable catalyst e.g. and preferably water soluble persulfates such asammonium and sodium and potassium persulfate and peroxides e.g. hydrogenperoxide; and also catalysts such as t-butyl perbenzoate and tbutylhydroperoxide, as well asother oil soluble materials such asbisazobutyronitrile and cumene hydroperoxide. Following reaction for therequired periodand at temperatures between 130200 F and boiling thereaction mixture is cooled and neutralized with alkali. The latex may bespray or otherwise dried without loss of dispersibility or' stability inliquid household bleach.

In the preparation of brightener protective polymer particles accordingto the present invention the hydrophobic monomer e. g. styrene isdivided into two portions for separate, sequenced emulsionpolymerizations. The first portion, for the first emulsionpolymerization comprises a major weight proportion, but less than all ofthe styrene to be used in forming the polymer, i.e. at least 50 percentby weight of the 65 to 98 parts by weight of styrene ultimately to beused per 100 parts of polymer is employed in the first polymerization.All of the optical brightener to be incorporated in the polymer isdissolved in this first portion of styrene. As indicated elsewhere thiswill be from 0.5 to 5 percent by weight of brightener com- .pound basedon the total weight of styrene monomer in the polymer. Preferably atleast 1 percent by weight of brightener is dissolved in the firststyrene portion. The first styrene portion will generally be less thanpercent by weight of the total polymer styrene content and willtypically be between 60 and 80 percent by weight of the polymer totalstyrene content.

The acrylic or methacrylic acid comonomer may also be divided into twoportions for sequential polymerization. The first portion employed inthe first polymerization, will be a major weight proportion of the acidin the total polymer i.e. at least 50 percent by weight of total polymeracid. This first portion may range up to percent by weight of the totalpolymer portion of acrylic or methacrylic acid, but typically from 60 to80 percent of the total polymer acid will be included in the first acidportion.

As mentioned above from five to 10 parts by weight of the styrenemonomer may be replaced on a weight for weight basis by certainhydrophilic comonomers. This substitution may be made in either thefirst or second styrene monomer portion, and preferably from 60 to 80percent by weight of the five to parts of hydrophilic comonomer, isused, is incorporated in the first styrene portion.

The balance of each monomer comprises a second portion for use in thesecond emulsion polymerization.

With the monomers having been thus divided for two polymerizations, theoptical brightener is dissolved in the styrene monomer first portion.The acid first portion is dissolved in water and the two solutions aremixed together in a suitable vessel. The mixture is emulsion polymerizedby the conventional techniques above described by adding a surfactant, apolymerization catalyst and heating. Heating is initially to about 130F, but the temperature rises with the reaction exotherm to about 190 F,or somewhat higher or lower. The first reaction product is a latex ofstyrene-acid polymer (or terpolymer with the hydrophilic comonomer)having from 30 to 60 percent by weight of polymer present as particlessuspended in an aqueous medium.

The reaction product is cooled before the next stage of polymerization.Cooling typically will be to less than 130 F. or the reaction initiationtemperature of the second polymerization mixture. The reaction mixtureis prepared by adding the balance of each of the monomers to the cooledfirst polymerization reaction product. The mixture is mixed together andpermitted to stand from to minutes or longer. Thereupon additionalpolymerization catalyst is added and the temperature of the reactionmixture permitted to rise above 130 to 190 F or higher or lower, withthe reaction exotherm. Reaction is continued to produce a latexcontaining polymer particles having an average particle size between 0.1and 2 microns. The optical brightener is within these particles andprotectively carried there. Suitable surfactants for effecting emulsionpolymerization as described and/or for suspending the finely particulatepolymer in bleach or other aqueous liquid are the noncationic types i.e.anionic, nonionic or amphoteric. Various of these surfactants will showgreater or less tolerance for the harsh environment of liquid householdbleach, depending on the concentration and pH thereof.

Among suitable surfactants are anionic aromatic compounds, e.g.watersoluble higher alkyl aryl sulfonates particularly those having fromeight to about 15 carbon atoms in the alkyl group. It is preferred touse the higher alkyl benzene sulfonates, although other mononuclear arylnuclei, such as toluene, xylene, or phenol, may be used also. The higheralkyl substituent on the aromatic nucleus may be branched orstraight-chained in structure, examples of such group being nonyl,dodecyl and pentadecyl groups derived from polymers of lowermono-olefins, decyl, keryl, and the like.

Illustrative of suitable aliphatic anionic compounds are the normal andsecondary higher alkyl sulfates, particularly those having about eightto 15 carbons in the fatty alcohol residue, such as lauryl (or coconutfatty alcohol) sulfate. Other suitable members of this class are thesulfuric acid esters of polyhydric alcohols incompletely esterified withhigher fatty acids; the oleic acid ester of isethionic acid; the higherfatty acid (e.g. coconut) ethanolarnide sulfates; the higher fatty acidamides of amino alkyl sulfonic acids, e.g. lauric acid amide of taurine;and the like.

These sulfates and sulfonates are used in the form of theirwater-soluble salts, such as the alkali metal and nitrogen-containing,e.g. lower alkylolamine, salts. Examples are the sodium, potassium,ammonium, isopropanolamine, monoand triethanolamine salts of said higheralkyl benzene sulfonate, higher alkyl sulfate and the like.

Typical specific examples are: the sodium salt of a sulfate ester of analkylphenoxypoly (ethyleneoxy) ethanol, the ammonium salt of thissulfate ester, sodium methyl oleyl taurate, sodium alkyl naphthalenesulfonate, alkyl acyl sodium sulfonate, sodium tetraphydronaphthalenesulfonate, sodium alkyl aryl sulfonate, alkyl amido sulfate,cocomonoglyceride sulfate, dodecylbenzene sodium sulfonate,dodecylbenzene oxide groups. it is preferred to use the polyoxyethylenecon- 7 sulfonic acid, tridecylbenzene sodium sulfonate, fatty alcoholsodium sulfate, sodium dodecyl diphenyl oxide disulfonate. sulfonatedcastor oil, polyethoxyalkyl phenol sulfonatc triethanolamine salts,sodium triethanolamine alkyl aryl sulfonate, magnesium lauryl sulfate,potassium lauryl sulfate, sodium lauryl ether sulfate, ammonium laurylether sulfate, sodium tallow sulfate, dodecylbenzene sodium sulfonate,oleyl methyl tauride, ammonium lauryl sulfate, amide sulfonate, and thelike.

In general, suitable nonionic surfactants include those such as producedby the introduction of alkylene oxide group into an organic hydrophobiccompound or group having an aliphatic or aromatic structure. Thehydrophobic organic group generally contains at least eight carbon atomsand up to about 30 carbon atoms. Condensed with the hydrophobic groupare at least five and preferably up to about 50 alkylene densatesderived from ethylene oxide. It is preferred to use the polyalkyleneoxide condensates of alkyl phenol, such as the polyoxyethylene ethers ofalkyl phenols having an alkyl group of at least about six, and usuallyabout eight to l2 carbons, and preferably 8 to 9 carbon atoms, and anethylene oxide ratio (No. of moles per phenol) of about 7.5, 8.5, 11.5or 20, though the number of ethylene oxide groups will he usually fromabout eight to 40. The alkyl substituent on the aromatic nucleus may bedi-isobutylene, diamyl, polymerized propylene, dimer-ized Q, C, olefin,and the like.

Further suitable nonionics are the polyoxyalkylene esters of organicacids, such as the higher fatty acids, rosin acids, tall oil acids, oracids from the oxidation of petroleum, et cetera. These polyglycolesters will contain usually from about 12 to about 30 moles of ethyleneoxide or its equivalent and about eight to 22 carbons in the acyl group.Suitable products are refined tall oil condensed with 16 or 20 ethyleneoxide groups, or similar polyglycol esters of lauric, stearic, oleicacids, etc.

Additional nonionic agents are the polyalkylene oxide condensates withhigher fatty acid amides, such as the higher fatty acid primary amides,monoand di-ethanolamides. Suitable agents are coconut fatty acid amidecondensed with about 10 to 50 moles of ethylene oxide. The fatty acylgroup will have similarly about 8 to 22 carbons, and usually about 10 to18 carbon atoms, in such products. The corresponding sulfonamides may beused also if desired.

Other suitable polyether nonionics are the polyalkylene oxide ethers ofhigh aliphatic alcohols. Suitable fatty alcohols having a hydrophobiccharacter, preferably eight to 22 carbons, are lauryl, myristyl, cetyl,stearyl and oleyl alcohols which may be condensed with an appropriateamount of ethylene oxide, such as at least about 6, and preferably about10 to 30 moles. A typical product is oleyl alcohol condensed with aboutl2, 15 or 20 moles of ethylene oxide. The corresponding higher alkylmercaptans or thioalcohols condensed with ethylene oxide are suitable inthe present invention also. The water-soluble polyoxyethylenecondensates with hydrophobic polyoxypropylene glycols may be employedalso, e.g. the ethylene oxide condensates with condensates of propyleneoxide and propylene glycol.

Further suitable nonionic materials are the higher fatty acidalkanolarnides, such as the monoethanolamides, diethanolamides andisopropanolamides wherein the acyl radical has about 10 to 14 carbonatoms and amine oxides. Examples are coconut (or equivalent latu'ic),capric and myristic diethanolamide, monoethanolamide andisopropanolamide, dodecyl dimethyl amine oxide and dimethylac'etoxyalkylamine oxide where alkyl is C C Generally, these surfactantscomprise from 0.05 to 10 per cent by weight, and preferably from 0.5 to3 percent of the reaction mixture and the latex added to the liquidhousehold bleach.

The optical brighteners useful herein include that species of dyes whichare fluorescing compounds, generally optically colorless andnonabsorptive in the visible portion of the spectrum. Generally,suitable brighteners are aromatic or heterocyclic compounds having aseries of conjugated double bonds.

Primary among typical compounds useful herein are:

I. The derivatives of 4,4- diaminostilbene -2,2 disulfonic acid,particularly the bistriazinyl, bisacyl and mixed acyl triazinylderivatives. Napthotriazolylstilbene sulfonic acid may be mentioned.Azinyl radicals may be substituted on the carbons of the heterocyclicring with many radicals including hydroxy, amino, alkoxy, hydroxyalkoxy,chloro, thio, alkoxybenzoyl, anilino, morpholino and others. Acylradicals include acetyl, phenoxyacetyl, alkoxybenzoyl toluyl, benzoyland aminobenzoyl. Benzoyl acyl radicals are generally substituted in theortho and/or para position e.g. with p-acetamino, methyl, methoxy,acetoxy, 2-hydroxyethoxy, haloalkoxy or alkenyloxy groups. The sulfonicacid group substituent in the stilbene may be replaced with an electrondonor radical such as alkyl, alkoxy or sulfamyl;

11. The derivatives of dibenzothiophene-S,5-dioxide, specifically3,7-diaminodibenzothiophene 2,8-disulfonic acid-5,5- dioxide in whichthe preferred acyl groups are alkoxybenzoyl groups. See e.g. US. Pat.Nos. 2,563,795; 2,573,652; 2,702,759; 2,719,155; and 2,733,165 which areincorporated herein by reference; and

Ill. The azoles, prepared generally by diazotization of 4-aminostilbene-Z-sulfonic acid, coupling with an orthocouplingnaphthylamine derivative (or benzene or a heterocylic) and oxidation tothe triazole. See US. Pat. Nos. 2,784,197; 2,713,057; 2,817,665;2,784,184; 2,972,611; 2,640,056; 2,639,990; British Pat. No. 808,113;Belgian Pat. No. 572,498; US. Pat. No. 2,765,304; 2,765,239; and GermanPat. No. 735,478, which are incorporated herein by reference; e.g.naphthotriazole, bis-benzimidazolyl compounds and benzimidazole;

lV. Coumarin and derivatives;

V. Pyrazine and derivatives; and

VI. 4-Aminonaphthalimide.

In addition, dyes and pigments may be used in place of or with theforegoing e.g. chromates, polysulfides, thianaphthanones andphthalocyanine such as potassium dichromate, Ultramarine blue,Sulfanthrene Pink FFD Paste and Monastral Fast Green GWD, for thepurpose of contributing blue" light or various tints. As used herein theterm brightener compound" is intended to be inclusive of these colorantsas well as the fluorescing, colorless dyes.

The presently described means for protectively carrying brightenersfinds particular application in liquid household bleach. Such productmay be opacified and fabrics cleaned therewith brightened byincorporation of brightener containing polymer in accordance with thisinvention. Bleach herein refers to any hypochlorite ion containingsolution containing sufficient free alkali to have a pH of 10 andpreferably 1 1.5 and higher, typically from 0.1 to 1.0 percent by weightfree alkali. Per cent concentrations of hypochlorite ion will rangebetween 1 and 10 per cent by weight with a practical minimum being 2.5percent. Most bleaches fall between 3 and 7 percent hypochlorite ion,and this concentration is most suited to use of the invention. Variousbleaching agents including the heterocyclic N-chlorimides, such as thefollowing are useful herein: trichlorocyanuric acid, dichlorocyanuricacid and salts thereof such as the alkali metal salts e.g. sodium andpotassium tri-acid dichlorocyanurates. Other imides are hypochlorite iongenerating also in aqueous solution and may be used e.g.N-chlorosuccinimide, N-chloromalonimide, N- chlorphthalimide andN-chloronaphthalimide. Other materials are the hydantoins e.g. the1,3-dichloro-5,5-dimethyl hydantoin, N-monochloro-C,C-dimethylhydantoin, methylene bis (N-chloro-C, C-dimethyl-hydantoin),1,3-dich1oro-5- methyl--isobutyldimethylhydantoin, 1,3-dichloro-5methyl- 5-ethylhydantoin, 1,3-dichloro-S-ntethyl-Sn-amylhydantoin andthe like as well as trichloromelamine. Preferred sources of hypochloriteion are the water soluble inorganic salts such as lithium, calcium,potassium and particularly sodium hypochlorite.

The invention is illustrated by the following Examples, in which allparts and percentages are by weight.

EXAMPLE 1 A. Polymer Preparation Dissolve five parts of dioctyl ester ofsodium sulfosuccinic acid and two parts of tetrasodium N-(1,2-dicarboxyethyl)l\loctadecyl-sulfosuccinamate in 700 parts of water.To this add 50 parts of methacrylic acid followed by 30 parts of a 25percent aqueous solution of sodium vinyl sulfonate. Dissolve five partsof Calcofluor ALF (optical brightener compound) in 250 parts of styrene.Emulsify the styrene solution in the aqueous phase and carry out thepolymerization by heating the emulsion to 130 F and adding 1 part ofsodium persulfate catalyst. The temperature rises to about l-200 F fromthe exothermic heat of reaction. Cool to 130 F and add 30 parts of a 25percent aqueous solution of sodium vinyl sulfonate followed by 250 partsof styrene. Stir for 30 minutes holding at 130 F and then add catalystand polymerize the second monomer addition with the heat of the exothermand cool.

B. Bleach Resistance Add 0.5 percent of the latex obtained in Part A toa 5 percent aqueous solution of sodium hypochlorite. Fluorescence isevaluated at periodic intervals. The bleach shows fluorescence initiallyand for 3 months at 70 F, the normal shelf life for bleach. Fabricwashed with the bleach shows greater whitening (brightening) both onvisual and instrumental inspection.

CONTROL 1 Example 1 was duplicated except that all the vinyl sulfonate(15 parts) and all the styrene (500 parts) with the brightener dissolvedtherein were added to the first polymerization mixture. After the onestage emulsion polymerization the obtained latex was added to bleach asin Part B of Example 1. Fluorescence was initially detectable under UVlight, but after 4 hours at 70 F no further fluorescence is detected,showing that the brightener had been destroyed.

EXAMPLE 2 Duplicate Example 1 but employ 300 parts of vinyl toluene inthe first polymerization reaction mixture and 200 parts thereof in thesecond polymerization reaction mixture, in place of the styrene inExample 1. In Part 8, evaluation of fluorescence shows continuingfluorescence after three months at 70 F.

EXAMPLE 3 Duplicate Example 1 but employ 30 parts of acrylic acid in thefirst polymerization reaction mixture and 20 parts in the secondpolymerization reaction mixture. A bleach stable brightener containinglatex is obtained.

CONTROL ll Duplicate Example 1 but mix the methacrylic acid first withstyrene and then add to the aqueous surfactant solution, followed byheating to polymerize. In part B, the emulsion which had similar sizeparticles and the same milky appearance prior to addition to the bleachas the Example emulsion, shows immediate physical deterioration andquickly demulsifies and settles as a flocculated mass in the holdingvessel.

I claim:

1. Method of combining an optical brightener compound with syntheticorganic polymer consisting essentially per parts by weight of 65 to 98parts of a styrene monomer selected from the group consisting ofstyrene, bromostyrene, chlorostyrene and alkyl substituted styrenehaving up to 12 carbon atoms and two to 35 parts of a water solublemonocarboxylic vinyl acid having three to four carbon atoms to retainoptical brightening properties in aqueous bleach solutions, whichincludes the steps of:

a. dissolving optical brightener compound in a major weight proportionbut less than 90% by weight of said styrene monomer;

b. dissolving at least a major weight proportion of said vinyl acid inwater;

c. combining the optical brightener containing styrene monomer from step(a) with the aqueous vinyl acid solution of step (b);

d. emulsion polymerizing the mixture of step (c) to form a copolymerlatex incorporating the optical brightener compound in the particulatecopolymer so formed;

e. adding the balance of the styrene monomer and the balance of thevinyl acid monomer, if any, to the latex from step (d), and

f. emulsion polymerizing the added monomers in step (e) onto thecopolymer particles from step (d).

2. Method according to claim 1 in which from 0.5 to percent by weight ofthe optical brightener compound is dissolved in the styrene monomer instep (a) based on the total weigh of the monomer incorporated in thepolymer.

3. Method according to claim 1 including maintaining a reactiontemperature above about 130 F in the polymerization mixture during steps(d) and (f).

4. Method according to claim 3 including also cooling the reactionmixture to less than 130 F between step (d) and step (f).

5. Method according to claim 1 including forming particles in step (f)having an average particle size between 0.1 and 2 microns.

6. Method according to claim 1 including also adding from 0.5 to 25parts of a hydrophylic monomer selected from acrylic monomers selectedfrom the hydroxyester, ether, amide and cyano derivatives of methacrylicand acrylic acid and vinyl sulfonate monomers having the formula R-CHCH-SO Me in which R is hydrogen or a hydrocarbon radical free ofaliphatic unsaturation having up to carbon atoms and Me is an alkalimetal, in place of an equal weight amount of the styrene monomer.

7. Method according to claim 1 in which said optical brightener compoundis selected from 4,4-diaminostilbene- 2,2'-disulfonic acids,dibenzothiophene-S,S-dioxides, azoles,

' coumarin, pyrazine, and 4-aminonaphthalimides.

8. Method of combining an optical brightener compound with syntheticorganic polymer consisting essentially per 100 parts by weight of 88 to92 parts of styrene and eight to 12 parts of an acrylic or methacrylicacid to retain optical brightening properties in aqueous bleachsolutions, which includes the steps of:

a. dissolving at least 10% by weight based on the total amount ofstyrene in the polymer of an optical brightener compound selected from4,4-diaminostilbene-2,2'-disulfonic acid derived,dibenzothiophene-5,S-dioxide derived, and azole derived opticalbrightener compounds in from 60 to 80 percent by weight of the totalstyrene monomer;

b. dissolving from 50 to 100% by weight of the total acrylic ormethacrylic monomer in water;

c. combining the optical brightener containing styrene from step (a) andthe aqueous vinyl acid solution of steps (b) with surfactant to form anemulsion polymerization mixture;

d-l. heating the mixture of step (c) to an elevated temperature lessthan 130 F in the presence of a polymerization reaction catalyst andreacting the monomers at the temperatures of the exotherrn;

d-2. cooling the polymerization reaction mixture to less than 130 F;

e. adding the balance of the styrene and acrylic acid or methacrylicacid monomer and maintaining at less than 130 F for at least 15 minutesfollowing addition;

f. adding additional polymerization catalyst to the reaction mixtureheating the mixture with the ensuing exotherm to a temperature above 130F to polymerize the added styrene monomer onto the polymer of step (d-l)to form a particulate polymer having an average particle size between0.1 and 2 microns which protectively incorporates said brightenercompound.

9. Method according to claim 8 including also substituting for a likeweight amount of styrene in step (a) from 60 to percent by weight offrom five to 10 parts per 100 parts of polymer of an acrylic monomerselected from the hydroxyester, ether, amide and cyano derivatives ofacrylic or methacrylic acid or a vinyl sulfonate monomer having theformula R-CH CH-SO Me in which R is hydrogen or an aromatic or alkylradical having up to 10 carbon atoms and Me is an alkali metal andincorporating the balance of said acrylic or sulfonate monomer into thereaction mixture in step (e).

10. Method according to claim 9 in which said polymer contains from 0.5to 5 percent by weight of said optical brightening compound, based onthe weight of styrene in the polymer.

1 l. Particles for protectively carrying oxidizer sensitive opticalbrightening compounds in aqueous bleach said particles comprising aninner portion consisting essentially of an oxidizer sensitive compoundand a styrene-acrylic polymer and an outer portion forming anencapsulating layer over the inner portion and consisting essentially ofstyrene polymer free of said compound, said particles comprising per 100parts of polymer from 65 to 98 parts of a styrene monomer selected fromthe group consisting of styrene, bromostyrene, chlorostyrene and alkylsubstituted styrenes having up to 12 carbon atoms and conversely from 2to 35 parts of methacryb ic or acrylic acid monomer copolymerizedtherewith, said inner portion polymer containing a major proportion butless than percent by weight of said styrene and at least a major weightproportion of said acid monomers, said outer portion polymer containingthe balance of said monomers.

12. Particles according to claim 11 in which said particles contain from0.5 to 5 percent by weight of said compound based on the weight of thestyrene in said polymer.

l3. Particles according to claim 11 in which said optical brightenercompound is selected from the group consisting of 4,4diaminostilbene-2,2-disulfonic acid, dibenzothiophene- 5,5-dioxidesazoles, coumarin, pyrazine, and 4- aminonaphthalimide.

l4. Particles according to claim 11 in which said particles have anaverage particle size between 0.5 and 2 microns.

15. Particles according to claim 11 in which said particles comprise perparts from 88 to 92 parts of styrene monomer and from eight to 12 partsof methacrylic or acrylic acid.

16. Particles according to claim 15 in which said inner portion containsfrom 60 to 80 weight percent of said styrene and from 50 to 100 weightpercent of said acid.

17. Particles according to claim 16 including also from five to 10 partsby weight per 100 parts of polymer in replacement of a like amount ofstyrene of a hydrophilic monomer selected from the hydroxy-ester, ether,amide and cyano derivatives of acrylic or methacrylic acid or a vinylsulfonate monomer having the formula RCH CHSO Me in which R is hydrogenor an aromatic or alkyl radical having up to 10 carbon atoms and Me isan alkali metal.

18. Particles according to claim 11 including also from five to 10 partsby weight per 100 parts of polymer in replacement of a like amount ofstyrene of a hydrophilic monomer selected from the hydroxy-ester, ether,amide and cyano derivatives of acrylic or methacrylic acid or a vinylsulfonate monomer having the formula RCH CH-SO Me in which R is hydrogenor an aromatic or alkyl radical having up to 10 carbon atoms and Me isan alkali metal.

19. Particles for protectively carrying an optical brightener compoundselected from the group consisting of 4,4-diaminostilbine-2,2-disulfonic acids, dibenzothiophene-5,5- dioxides andazoles in aqueous bleach comprising particles of an average particlesize between 0.5 and 2 microns and having a center portion consistingessentially of said brightener compound in an amount between 0.5 and 5percent by weight based on the styrene weight in the particles and astyreneacrylic copolymer and an outer encapsulating layer formed overthe center portion and consisting essentially of styrene polymer free ofsaid compound, said particles consisting essentially of from 65 to 98parts of styrene and from two to 35 selected from the hydroxyester,ether, amide and cyano derivatives of acrylic or methacrylic acid or avinyl sulfonate monomer having the formula R-CH CHSO Me in which R ishydrogen or an aromatic or alkyl radical having up to 10 carbon atomsand Me is sodium or potassium, said center portion containing from 60 topercent of said hydrophilic comonomer and said outer portion the balancethereof.

III l l i

2. Method according to claim 1 in which from 0.5 to 5 percent by weightof the optical brightener compound is dissolved in the styrene monomerin step (a) based on the total weight Of the monomer incorporated in thepolymer.
 3. Method according to claim 1 including maintaining a reactiontemperature above about 130* F in the polymerization mixture duringsteps (d) and (f).
 4. Method according to claim 3 including also coolingthe reaction mixture to less than 130* F between step (d) and step (f).5. Method according to claim 1 including forming particles in step (f)having an average particle size between 0.1 and 2 microns.
 6. Methodaccording to claim 1 including also adding from 0.5 to 25 parts of ahydrophylic monomer selected from acrylic monomers selected from thehydroxyester, ether, amide and cyano derivatives of methacrylic andacrylic acid and vinyl sulfonate monomers having the formulaR-CH=CH-SO3Me in which R is hydrogen or a hydrocarbon radical free ofaliphatic unsaturation having up to 10 carbon atoms and Me is an alkalimetal, in place of an equal weight amount of the styrene monomer. 7.Method according to claim 1 in which said optical brightener compound isselected from 4,4''-diaminostilbene-2,2''-disulfonic acids,dibenzothiophene-5,5-dioxides, azoles, coumarin, pyrazine, and4-aminonaphthalimides.
 8. Method of combining an optical brightenercompound with synthetic organic polymer consisting essentially per 100parts by weight of 88 to 92 parts of styrene and eight to 12 parts of anacrylic or methacrylic acid to retain optical brightening properties inaqueous bleach solutions, which includes the steps of: a. dissolving atleast 10% by weight based on the total amount of styrene in the polymerof an optical brightener compound selected from4,4''-diaminostilbene-2,2''-disulfonic acid derived,dibenzothiophene-5,5-dioxide derived, and azole derived opticalbrightener compounds in from 60 to 80 percent by weight of the totalstyrene monomer; b. dissolving from 50 to 100% by weight of the totalacrylic or methacrylic monomer in water; c. combining the opticalbrightener containing styrene from step (a) and the aqueous vinyl acidsolution of steps (b) with surfactant to form an emulsion polymerizationmixture; d-1. heating the mixture of step (c) to an elevated temperatureless than 130* F in the presence of a polymerization reaction catalystand reacting the monomers at the temperatures of the exotherm; d-2.cooling the polymerization reaction mixture to less than 130* F; e.adding the balance of the styrene and acrylic acid or methacrylic acidmonomer and maintaining at less than 130* F for at least 15 minutesfollowing addition; f. adding additional polymerization catalyst to thereaction mixture heating the mixture with the ensuing exotherm to atemperature above 130* F to polymerize the added styrene monomer ontothe polymer of step (d-1) to form a particulate polymer having anaverage particle size between 0.1 and 2 microns which protectivelyincorporates said brightener compound.
 9. Method according to claim 8including also substituting for a like weight amount of styrene in step(a) from 60 to 80 percent by weight of from five to 10 parts per 100parts of polymer of an acrylic monomer selected from the hydroxyester,ether, amide and cyano derivatives of acrylic or methacrylic acid or avinyl sulfonate monomer having the formula R-CH=CH-SO3Me in which R ishydrogen or an aromatic or alkyl radical having up to 10 carbon atomsand Me is an alkali metal and incorporating the balance of said acrylicor sulfonate monomer into the reaction mixture in step (e).
 10. Methodaccording to claim 9 in which said polymer contains from 0.5 to 5percent by weight of said optical brightening compound, based on theweight of styrene in the polymer.
 11. ParTicles for protectivelycarrying oxidizer sensitive optical brightening compounds in aqueousbleach said particles comprising an inner portion consisting essentiallyof an oxidizer sensitive compound and a styrene-acrylic polymer and anouter portion forming an encapsulating layer over the inner portion andconsisting essentially of styrene polymer free of said compound, saidparticles comprising per 100 parts of polymer from 65 to 98 parts of astyrene monomer selected from the group consisting of styrene,bromostyrene, chlorostyrene and alkyl substituted styrenes having up to12 carbon atoms and conversely from 2 to 35 parts of methacrylic oracrylic acid monomer copolymerized therewith, said inner portion polymercontaining a major proportion but less than 90 percent by weight of saidstyrene and at least a major weight proportion of said acid monomers,said outer portion polymer containing the balance of said monomers. 12.Particles according to claim 11 in which said particles contain from 0.5to 5 percent by weight of said compound based on the weight of thestyrene in said polymer.
 13. Particles according to claim 11 in whichsaid optical brightener compound is selected from the group consistingof 4, 4'' diaminostilbene-2,2''-disulfonic acid,dibenzothiophene-5,5-dioxides azoles, coumarin, pyrazine, and4-aminonaphthalimide.
 14. Particles according to claim 11 in which saidparticles have an average particle size between 0.5 and 2 microns. 15.Particles according to claim 11 in which said particles comprise per 100parts from 88 to 92 parts of styrene monomer and from eight to 12 partsof methacrylic or acrylic acid.
 16. Particles according to claim 15 inwhich said inner portion contains from 60 to 80 weight percent of saidstyrene and from 50 to 100 weight percent of said acid.
 17. Particlesaccording to claim 16 including also from five to 10 parts by weight per100 parts of polymer in replacement of a like amount of styrene of ahydrophilic monomer selected from the hydroxy-ester, ether, amide andcyano derivatives of acrylic or methacrylic acid or a vinyl sulfonatemonomer having the formula R-CH=CH-SO3Me in which R is hydrogen or anaromatic or alkyl radical having up to 10 carbon atoms and Me is analkali metal.
 18. Particles according to claim 11 including also fromfive to 10 parts by weight per 100 parts of polymer in replacement of alike amount of styrene of a hydrophilic monomer selected from thehydroxy-ester, ether, amide and cyano derivatives of acrylic ormethacrylic acid or a vinyl sulfonate monomer having the formulaR-CH=CH-SO3Me in which R is hydrogen or an aromatic or alkyl radicalhaving up to 10 carbon atoms and Me is an alkali metal.
 19. Particlesfor protectively carrying an optical brightener compound selected fromthe group consisting of 4,4''-diaminostilbine-2,2''-disulfonic acids,dibenzothiophene-5,5-dioxides and azoles in aqueous bleach comprisingparticles of an average particle size between 0.5 and 2 microns andhaving a center portion consisting essentially of said brightenercompound in an amount between 0.5 and 5 percent by weight based on thestyrene weight in the particles and a styrene-acrylic copolymer and anouter encapsulating layer formed over the center portion and consistingessentially of styrene polymer free of said compound, said particlesconsisting essentially of from 65 to 98 parts of styrene and from two to35 parts of methacrylic or acrylic acid copolymerized therewith saidcenter portion containing from 60 to 80 weight percent of the styrenepresent in said particles and from 50 to 100 percent of the acid presentin said particles, said outer portion containing the balance of thestyrEne and acid present in the particles.
 20. Particles according toclaim 19 including also in replacement of a like weight amount ofstyrene in said particles from 5 to 10 parts by weight of a hydrophiliccomonomer selected from the hydroxyester, ether, amide and cyanoderivatives of acrylic or methacrylic acid or a vinyl sulfonate monomerhaving the formula R-CH=CH-SO3Me in which R is hydrogen or an aromaticor alkyl radical having up to 10 carbon atoms and Me is sodium orpotassium, said center portion containing from 60 to 80 percent of saidhydrophilic comonomer and said outer portion the balance thereof.